The overall objectives of this project are to investigate the mechanism of action and biological significance of cell-cell adhesion molecules (CAMs) during development. The major focus of this work is the neural cell adhesion molecule (NCAM), which is a broadly distributed cell surface protein believed to influence a wide variety of cell interactions. The approach involves of purified cell surface glycoproteins, membrane vesicles, cultured cells and explants, and intact chicken embryos. Studies focus on characterization of the structure of NCAM and of cell-cell bonds involving this molecule, as well as attempts to relate natural or induced variations in the expression or structural form of NCAM and other CAMs to changes in tissue structure. The following specific aims are proposed: 1. Development and characterize reagents required to study NCAM both in this and other laboratories. 2. Identify the molecular interactions involved in formation of an NCAM-mediated cell-cell bond. 3. Test the hypothesis that NCAM and other adhesion molecules in neurite outgrowth and fasciculation. 5. Develop a model cell culture system for study of CAMs, utilizing neuroblastoma-sensory ganglion neuron hybrids. 6. Continue the use of adhesion-perturbing antibodies and enzymes to relate chemical and in vitro observation to the in vivo development of tissues.